USB 2.0 Data Transfer Rates

[Twisties]

So, USB 2.0 should be capable of something like 60 mB a second. I get rates somewhere between 1 and 17 mB/s depending what device I'm using.

 

About 1 mb/s with the Creative Zen 60. Up to 17 with a brand new 500 gB external HD and also with Class 6 SDHC cards (using a sandisk SDHC to USB interface). The older (2 yoa) 120 mb external HD gets about 3 or so mB/s. Transfer directly off of cameras is really slow.

 

Running XP (fully updated), machine is a 1.5 yoa AMD dual processor setup w/USB 2.0 on the motherboard. Typically just a nice short USB cable, 4 to 6 feet.

 

So, why so slow? Anything to do about it?

 

TIA,

 

Jan

 

 

[Bob Palin]

Try turning off the machine then unplugging everything except the USB2 device and restart. Some USB controllers are dumb enough to bring the speed down to 1.0 level for all ports if any ports have 1.0 device.

[smiller]

60 megabytes per second (I guess you derived that from the standard 480 megabit per second spec of USB 2.0) is the maximum theoretical speed, but that's usually (actually never, because of overhead) realized in the real world. Even the high-speed burst mode is less than a true 480 mbps, and not always supported by a device, and the more common 'full speed' mode is considerably slower than that. Many devices cannot actually operate at a full USB 2.0 rate, and devices like cameras are relatively slow because they use flash memory. There are whole mess of considerations beyond the theoretical USB speed specification.

[Dave McReynolds]

On a related question, I use USB flash drives to do routine backup during the day - tax returns I am working on, office files, etc. I copy things to the flash dive up to a dozen or more times a day, as I typically back-up whatever I'm working on whenever I leave my desk for any reason.

 

As drives with more storage capacity became available, I bought new ones, up to 2 gigs. Until I found that it seemed to take significantly longer to store and retreive things from the 2 gig flash drives than from my older 256 mb drives. Since these are just temporary back-ups anyway, I really don't need a lot of storage capacity, so I went back to using my old 256 mb flash drives.

 

Do you think this is true, that it takes longer to store and retreive from a 2 gig flash drive than a 256 mb flash drive, or is something else going on here?

[smiller]

Do you think this is true, that it takes longer to store and retreive from a 2 gig flash drive than a 256 mb flash drive, or is something else going on here?

Dunno about that, I have seen some reports of large numbers of files slowing writes but I don't know if these cases have anything to do with your own usage pattern.

 

If speed is a concern you might try one of the tiny USB hard drives, these are much faster than flash.

[Jerry Johnston]

Dave here is a site that rated different flash drives. I thought it may interest you. Thumb drive test site

[Selden]

Do you think this is true, that it takes longer to store and retreive from a 2 gig flash drive than a 256 mb flash drive, or is something else going on here?

 

Absolutely; the bigger the flash drive, the longer it takes to mount or dismount. This seems to be true with both Windows and MacOS. I currently use a 4gb Lexar Firefly flash drive, but I don't plan on going any bigger. And older 512 mb FireFly is way faster.

 

The exception to this rule is that I recently acquired a new digital camera, and decided to get an 8 gb SDHC card for it, mainly to minimize swapping media, and have room for video clips. The card is mostly empty at this point, so I can't comment on how fast it will be in a card reader (which I prefer to using an interface cable between camera and computer).

 

I have a 2gb rotating media miniature hard drive (about the size of a Zippo lighter) that is about 4 years old, and I can't say that it seems any faster than the flash drive, but that may just reflect the age of the device.